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Cycloalkane Metathesis Using a Bi-Metallic System: Understanding the Effect of Second Metal in Metathesis Reaction

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Cycloalkane Metathesis Using a Bi-Metallic System: Understanding the Effect of Second Metal in Metathesis Reaction Cycloalkane Metathesis using a Bi-metallic System: Understanding the Effect of Second metal in Metathesis Reaction Thesis by Ahmed M. Alshanqiti In Partial Fulfillment of the Requirements For the Degree of Master of Science King Abdullah University of Science and Technology Thuwal, Kingdom of Saudi Arabia September, 2018 3 EXAMINATION COMMITTEE PAGE The thesis of Ahmed M. Alshanqiti is approved by the examination committee. Committee Chairperson: Prof. Jean Marie Basset Committee Members: Kuo-Wei Huang, Prof. Pascal Saikaly 4 © September, 2018 Ahmed M. Alshanqiti All Rights Reserved 5 ABSTRACT Cycloalkane Metathesis using a Bi-metallic System: Understanding the Effect of Second metal in Metathesis Reaction Ahmed M. Alshanqiti Over the past decades, since the discovery of a single–site silica-supported catalyst for the alkane metathesis reaction by our group, we have been extensively working on the development of supported catalytic systems for the improved alkane metathesis reaction. During these developments, we understand the reaction mechanism and reached a new perspective for the synthesis of various supported bimetallic systems via the surface organometallic chemistry (SOMC) approach. Recently, with this bi-metallic system, we got a very high TON (10000) in propane metathesis reaction. As these catalysts are very efficient for linear alkanes we thought to apply it for cyclo-alkanes specifically, for cyclo- octane metathesis expecting better activity. Besides, the value of the ring alkanes are higher than the linear alkanes. The current work demonstrates a combination of [(ΞSi−O−)W(Me)5] and [(ΞSi− O−)Ti(Np)3 pre-catalyst with several supports (SiO2-700, SBA-15 and MCM-41) for metathesis of cyclooctane. The catalysts have been synthesized and fully characterized by elemental 6 analysis (EA), FT-IR and NMR spectroscopies. After fully characterization the bi-metallic catalyst was tested for metathesis of cyclooctane with highest ever TON 2500 as compared to that of mono-metallic catalyst where we got 430 TON. Which again corroborates our prediction that bimetallic catalysts are better catalysts than monometallic catalysts. 7 ACKNOWLEDGEMENTS First and foremost, I pay my gratitude to Allah, the most merciful and the mighty, for all his blessings that allowed me to accomplish this work. One of his great blessings on me was supervision of Professor Jean-Marie Basset. I would certainly like to take this opportunity to express my sincere gratitude to him. Jean-Marie is a very knowledgeable person and well-known scholars in my field. He has given me priceless advice, suggestion, and wisdom. Under his precise supervision, I have benefited immensely from his constructive criticisms, supportive mentoring skills, and continuous encouragement. Without a doubt, this thesis would not have been possible without his help. Special recognition and appreciation should be given to Dr. Manoja Kumar Samantary who probably was involved in many aspects of this thesis, I am so grateful to him for his insightful discussions and comments. My appreciation is also extended to Aya Saidi for her great suggestions and wise advice. I would like to record my appreciation for the support and the cooperation received from Basset’s group members in catalysis center KCC. It was such a pleasure to work with them. I also would like to thank the members of my thesis examining committee, professor Kuo- Wei Huang, and professor Pascal Saikaly, for their valuable comments and suggestions. 8 I sincerely offer my profound gratitude to King Abdullah University of Science and Technology for offering me the chance of studying and for their continued generosity. My appreciation also goes to all my colleagues and staff members who I met. Last, but definitely not the least, I would like to express my very profound gratitude to my parents, my brothers, and sisters for the love, help, and encouragement to achieve my goals. 9 TABLE OF CONTENTS EXAMINATION COMMITTEE PAGE ...................................................................................... 3 COPY RIGHT PAGE …..…………………………………………………………………………………………………… 4 ABSTRACT ............................................................................................................................ 5 ACKNOWLEDGEMENTS ....................................................................................................... 7 TABLE OF CONTENTS........................................................................................................... 9 LIST OF ABBREVIATIONS ................................................................................................... 11 LIST OF ILLUSTRATIONS..................................................................................................... 12 LIST OF TABLES .................................................................................................................. 14 INTRODUCTION ................................................................................................................. 15 1.1. OVERVIEW OF CATALYSTS.......................................................................................... 15 1.1.1. Homogeneous Catalysis .............................................................................. 15 1.1.2. Heterogeneous Catalysis ............................................................................ 16 1.2. HETEROGENEOUS VS. HOMOGENEOUS CATALYSIS .......................................................... 16 1.3. SURFACE ORGANOMETALLIC CHEMISTRY (SOMC) ......................................................... 16 1.4. SINGLE-SITE HETEROGENEOUS CATALYST ..................................................................... 18 1.5. SOMC SUPPORTS ................................................................................................... 20 1.5.1. Silica-Supported .......................................................................................... 20 1.5.2. Alumina-Supported ..................................................................................... 21 1.6. METATHESIS OF ALKANES .......................................................................................... 22 1.7. METATHESIS OF ALKENES (OLEFINS) ........................................................................... 24 1.8. CHEMISTRY OF GROUP 5 AND 6 METALS ...................................................................... 25 EXPERIMENTS .................................................................................................................... 27 2.1. INTRODUCTION ....................................................................................................... 27 2.2. SILICA PREPARATION ................................................................................................ 27 2.3. TUNGSTEN(VI) HEXAMETHYL (WME6) ........................................................................ 28 2.4. TETRA NEOPENTYL TITANIUM COMPLEX [TI(NP)4]......................................................... 29 2.5. GRAFTING .............................................................................................................. 30 2.6. PROCEDURES OF METATHESIS REACTION ..................................................................... 31 10 2.7. CHARACTERIZATION OF THE SAMPLE BY INSTRUMENTS .................................................... 32 2.7.1. Fourier Transform Infra-Red Spectroscopy ................................................ 32 2.7.2. Elemental Analysis (EA) ............................................................................... 32 2.7.3. Nuclear Magnetic Resonance Spectroscopy (NMR) ................................... 33 2.7.4. Gas Chromatography and Gas Chromatography-Mass Spectrometer ....... 35 RESULTS AND DISCUSSION ............................................................................................... 37 3.1. INTRODUCTION ....................................................................................................... 37 3.2. LIQUID STATE NMR ................................................................................................. 37 3.3. SOLID STATE NMR .................................................................................................. 40 3.4. FOURIER TRANSFORM INFRA-RED SPECTROSCOPY (FTIR) ............................................... 44 3.5. ELEMENTAL ANALYSIS............................................................................................... 46 3.6. CYCLOALKANE METATHESIS ....................................................................................... 46 3.7. N-DECENE METATHESIS ............................................................................................ 49 CONCLUSION ..................................................................................................................... 51 4.1. OVERALL SUMMARY................................................................................................. 51 4.2. CONCLUSIONS ......................................................................................................... 52 4.3. FUTURE WORK ........................................................................................................ 53 REFERENCES ...................................................................................................................... 54 11 LIST OF ABBREVIATIONS CP/MAS Cross Polarization/ Magic Angle Spinning GC Gas Chromatography GC-MS Gas Chromatography mass spectrometry h hour(s) HVL High Vacuum Line IR Infra-Red ppm Part per million mg Milligram(s) mL Milliliter(s) mol Mole(s) mmol Millimole(s)
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